1. Field of the Invention
This invention relates to a tension locking mechanism of a retractor, and more particularly to a tension locking mechanism for locking and unlocking a webbing take-up force by electrical control means utilizing a solenoid.
2. Description of the Prior Art
There is generally known a tension locking mechanism of a retractor which uses cam means to cause a latch member to be engaged with a ratchet member integral with a webbing take-up reel to thereby lock a webbing take-up force after a predetermined series of webbing wearing operations. However, such a tension locking mechanism using cam means has suffered from a disadvantage that when it is desired to recover the webbing take-up force and take up webbing onto the take-up reel, the take-up force is not restored unless a predetermined webbing operation is effected. Such an operation is extremely cumbersome.
So, there is conceived a method which uses electrical means such as a solenoid to immmediately recover the take-up force by a simple webbing removing or releasing operation. In this case, however, when the solenoid becomes deenergized, a plunger is moved by a spring of a considerable spring force to bring the latch member to its non-latching position to thereby recover the take-up force and thus, subsequently, the plunger is returned to its original position by the energized solenoid against said considerable spring force, whereafter the latch member is brought to its latching position to thereby lock the take-up force. Therefore, the force which the plunger receives upon energization of the solenoid is required to be great, and this necessarily leads to a disadvantage that the solenoid becomes bulky and expensive.